Present day microwave receiving systems can be configured such that a single microwave antenna is connected to microwave receiving equipment. The signals received by the dedicated antenna which are input to the microwave receiving equipment usually have a noise component which accompanies the microwave signal. The microwave receiving equipment for any system of this type is generally chosen according to its sensitivity and the expectant signal to noise ratio of the incoming signal. That is, the microwave receiving equipment must have the proper signal to noise sensitivity to be able to distinguish between the microwave signal and noise component of the received signal. If the microwave receiving equipment has a sensitivity below the threshold signal to noise ratio of the incoming signal, the microwave receiving equipment can distinguish between the microwave signal and noise thereby allowing for signal capture. If, however, the sensitivity of the microwave receiving equipment is above the threshold signal to noise ratio of the incoming signal, there will not be signal capture resulting in noise being output from the microwave receiving equipment.
The prior art discloses systems or devices to test or diagnose certain receiver characteristics but none are useful for testing the purported sensitivity of microwave receiving equipment.
U.S. Pat. No. 4,004,230 discloses a device for evaluating receiver parameters such as sensitivity, bandpass characteristics and operating frequencies by injecting a modulated signal into the receiver under test. U.S. Pat. No. 4,125,809 discloses a system to measure the ratio of carrier power to noise power in a 1 Hz bandwidth of an earth coverage beacon signal. Japanese application No. 58-151734 discloses a receiver having a self-diagnosing means which has incorporated therein a noise generator which delivers a self-diagnosing signal to the receiver. However, these systems or devices, as stated, do not provide a test signal with a fixed separation between carrier and noise power levels which is injected into the microwave receiving equipment under test to test the purported sensitivity of the microwave receiving equipment as does the present invention.